Vue.component('tabs', {
    template: '\
        <div class="tabs">\
            <div class="tabs-bar">\
                <div\
                    :class="tabCls(item)"\
                    v-for="(item,index) in navList"\
                    @click="handleChange(index)">\
                    {{item.label}}\
                </div>\
            </div>\
            <div class="tabs-content">\
                <slot></slot>\
            </div>\
        </div>',
    props: {
        value: {
            type: [String, Number]
        }
    },
    data: function () {
        return {
            currentValue: this.value,
            navList: []
        }
    },
    methods: {
        tabCls: function (item) {
            return [
                'tabs-tab',
                {
                    'tabs-tab-active': item.name === this.currentValue
                }
            ]
        },
        getTabs() {
            return this.$children.filter(function (item) {
                return item.$options.name === 'pane';
            });
        },
        updateNav() {
            this.navList = [];
            var _this = this;

            this.getTabs().forEach(function (pane, index) {
                _this.navList.push({
                    label: pane.label,
                    name: pane.name || index
                });
                if (!pane.name) pane.name = index;
                if (index === 0) {
                    if (!_this.currentValue) {
                        _this.currentValue = pane.name || index;
                    }
                }
            });
        },
        updateStatus() {
            var tabs = this.getTabs();
            var _this = this;

            tabs.forEach(function (tab) {
                return tab.show = tab.name === _this.currentValue;
            })
        },
        handleChange: function (index) {
            var nav = this.navList[index];
            var name = nav.name;

            this.currentValue = name;
            this.$emit('input', name);
            this.$emit('on-click', name);
        }
    },
    watch: {
        value: function (val) {
            this.currentValue = val;
        },
        currentValue: function () {
            // 在当前选中的tab发生变化时，更新pane的显示状态
            this.updateStatus();
        }
    }
});